Adds support for prefix-variable in version-number wrapper

prefix-variable is currently not available for use in the version-number wrapper.
updated wrapper for support of this variable
and updated test fixtures to also use this variable.

set default value of prefix-variable to ''
Errors out without a default value set saying the attribute is missing,
and since this is an optional attribute we don't want that.

Task: 4885
Change-Id: I151eef271194fb38dfde7518698f2ff06e3a8f01

jenkins_jobs/modules/wrappers.py

@@ -2358,6 +2358,8 @@ def version_number(parser, xml_parent, data):
         number to (required)
     :arg str format-string: Format string used to generate version number
         (required)
+    :arg str prefix-variable: Variable that contains version number prefix
+        (optional)
     :arg bool skip-failed-builds: If the build fails, DO NOT increment any
         auto-incrementing component of the version number (default: false)
     :arg bool display-name: Use the version number for the build display
@@ -2387,6 +2389,7 @@ def version_number(parser, xml_parent, data):
         # option, xml name, default value
         ("variable-name", 'environmentVariableName', None),
         ("format-string", 'versionNumberString', None),
+        ("prefix-variable", 'environmentPrefixVariable', ''),
         ("skip-failed-builds", 'skipFailedBuilds', False),
         ("display-name", 'useAsBuildDisplayName', False),
         ("start-date", 'projectStartDate', '1970-1-1 00:00:00.0 UTC'),

tests/wrappers/fixtures/version-number001.xml

@@ -4,6 +4,7 @@
     <org.jvnet.hudson.tools.versionnumber.VersionNumberBuilder>
       <environmentVariableName>relVersion</environmentVariableName>
       <versionNumberString>${BUILD_DATE_FORMATTED, &quot;yy.M&quot;}.${BUILDS_THIS_MONTH_Z}</versionNumberString>
+      <environmentPrefixVariable>relVersion</environmentPrefixVariable>
       <skipFailedBuilds>false</skipFailedBuilds>
       <useAsBuildDisplayName>false</useAsBuildDisplayName>
       <projectStartDate>1970-1-1 00:00:00.0 UTC</projectStartDate>

tests/wrappers/fixtures/version-number001.yaml

@@ -1,4 +1,5 @@
 wrappers:
   - version-number:
       variable-name: relVersion
+      prefix-variable: relVersion
       format-string: ${BUILD_DATE_FORMATTED, "yy.M"}.${BUILDS_THIS_MONTH_Z}